Effect of cytoplasm on combining ability and yield attributes in pearl millet [Pennisetum glaucum (L.) R. Br.]
The effect of cytoplasm on productivity and combining ability for grain yield and its contributing traits was studied in 144 hybrids. Six male sterile (A) lines (81A and HMS 8A (A1), Pb3l3A (A2), Pb402A (A3), 81A4, 81A5 representing five different cytoplasm systems and their corresponding maintainer (B) lines were crossed with 12 restorer (R) lines in a line × tester design. The 24 parents (A+B and R) and 144 crosses were grown separately in contiguous block in randomized block design with two replications in six environments, three each (E1, E2, E3) and (E4, E5, E6) during 2000 and 2001, respectively. Analysis of variance revealed significant differences among genotypes, parents, lines (A, B), testers, hybrids (A × R, B × R). The differences due to A vs. B and A × R vs. B × R crosses were highly significant for grain yield/plant (g), harvest index (%) and growth rate (g/plant/day). Cytoplasmic effects were estimated by comparing A × R and B × R hybrids combination. Both positive and negative cytoplasmic effects were observed for all the four characters studied. The (A × R vs. B × R) × E component of variance exhibited significance for all the four characters. The effects were modified by environment. These were more pronounced for grain yield, 500-grain weight and harvest index, and positive cytoplasmic effects exceeded than the negative ones. For growth rate negative cytoplasmic effects were preponderant and significant only in one environment which is due to cytoplasm and nuclear genome interaction. Effect of cytoplasm was more or less equally pronounced on general combining ability effects of parents and specific combining ability of crosses. Array mean performance of 81A cytoplasmic iso-hybrids indicated that all the three cytoplasms have same potential, therefore, any of these cytoplasms can be used in hybrid breeding.
Cytoplasmic effects, combining ability, Pearl millet.